The following description of the background of the invention is provided simply as an aid in understanding the invention and is not admitted to describe or constitute prior art to the invention.
The invention relates to the simulation of deformation of materials, notably of soft body tissues.
Usually, a display interface is provided for representing at least one object following a predetermined shape, displayed with a selected grid pattern. A user interface provided with mechanical handling means allows the user to simulate one or more forces exerted globally on the object.
A memory is also provided for storing mechanical parameters of the material of which the object in question consists, data as to the position of the object, recorded at the vertices of a selected mesh, and force data which represent, in intensity and position, stress to be exerted on the object.
A computer operatively connected to the memory evaluates new positions of the vertices, as a function of the stress exerted and the mechanical parameters of the material. In order to display the deformation and/or the return to a resting position of the moving object, the computer calculates the evolution of the positions of the vertices over time as a function of this stress. When it is used to simulate the deformation (or cutting) of body tissues, a qualified person (such as a surgeon) is able to follow the simulation of a deformation and/or a return to a resting position.
In the published application no. FR-9714506 by this Applicant, the simulation of the deformations of the object was based on a linear model, in the embodiment described. Although the use of the apparatus described in FR-9714506 has proved very promising in the field of surgical assistance for simulating the cutting of soft body tissues (liver, skin, etc), the simulation of large movements, possibly non-linear, was not completely natural. Moreover, this apparatus could not predict the reaction to a force exerted on just any type of deformable material, particularly in the case of large movements.
Thus, simulated deformations with large shifts in position are not normally reliable. The present invention sets out to improve the situation.